Paeds · paediatric-dermatology
Congenital melanocytic naevi and pigmentary birthmarks
Also known as congenital melanocytic naevus · congenital melanocytic nevus · giant congenital melanocytic naevus · bathing trunk naevus · cafe-au-lait macule · dermal melanocytosis · Mongolian spot · nevus of Ota · nevus depigmentosus · neurocutaneous melanocytosis · satellite nevi · NRAS mosaicism
A fellowship approach to the congenital pigmentary birthmarks, built around the single decision that matters: separating the common benign lesion — the dermal melanocytosis, the isolated cafe-au-lait macule, and the small congenital melanocytic naevus — from the high-risk lesion that demands the specialist service. The page covers the size-based classification of the congenital melanocytic naevus (CMN) by the projected adult size, the size-risk relationship that concentrates the melanoma risk in the large and the giant CMN, the postzygotic NRAS mosaicism that produces the CMN and the neurocutaneous melanocytosis as a single neural-crest event, the recognition of the child at risk of the neurocutaneous melanocytosis, the differential of the cafe-au-lait macule of the NF1 and the McCune-Albright, the dermal melanocytosis mistaken for the bruise, and the ash-leaf macule of the tuberous sclerosis, and the surveillance and the management from the observation and the baseline photography to the surgery and the laser.
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Red flags
- A large or giant congenital melanocytic naevus on the posterior axis — the head, the neck, or the spine — especially with many satellite nevi, raises the concern for the neurocutaneous melanocytosis and warrants the specialist assessment and the consideration of the CNS imaging
- A new nodule, a colour change, a bleeding, or a rapid growth within a congenital melanocytic naevus demands the urgent assessment for the melanoma, because the melanoma risk in the CMN is concentrated in the childhood
- Six or more cafe-au-lait macules, each over five millimetres before puberty (over fifteen millimetres after puberty), meets the NIH criterion for the neurofibromatosis type 1 and warrants the full assessment
- A child with a large posterior-axis congenital melanocytic naevus who develops the headache, the seizure, the developmental regression, or the hydrocephalus has the symptomatic neurocutaneous melanocytosis, a neurological emergency with the poor prognosis
Life stages
Care settings
Clinical exam formats
Board mappings
- Dermatology - recognise the common congenital pigmentary birthmarks including the congenital melanocytic naevus, the cafe-au-lait macule and the dermal melanocytosis
- General paediatrics and preventive care - the reassurance of the benign birthmark, the baseline documentation, and the size measurement of the CMN
- Dermatology - the size-based risk stratification of the CMN, the neurocutaneous melanocytosis, and the multidisciplinary management of the large and the giant CMN
- Genetics and dysmorphology - the syndromic pigmentary birthmarks and the NF1, the McCune-Albright and the tuberous sclerosis assessment
- Dermatology 10-12
- Neonatology and the newborn examination 10-12
- Genetics 10-12
- Short Cases
- Long Cases
- Communication scenarios
- 8. Dermatology - the congenital and the acquired skin lesions including the congenital melanocytic naevi and the pigmentary birthmarks
- 1. Clinical assessment and the newborn and the infant skin examination
- 17. Late-onset problems and the long-term skin surveillance
- Foundation of Practice (FOP)
- Applied Knowledge in Practice (AKP)
- Clinical
- History
- Communication
- General Pediatrics Content Outline - Dermatology
- General Pediatrics Content Outline - Universal Task 3: Physical Examination and Universal Task 5: Patient Management
- Neonatology - the newborn skin examination
- Patient Care 5: Patient Management
- Medical Knowledge 2: Conditions common in pediatric primary care including the congenital naevi and the pigmentary birthmarks
- Systems-Based Practice 1: the multidisciplinary and the specialist referral for the high-risk lesion
- Medical Expert
- Pediatrics: Dermatology and the Genetics applied domain
A six-week-old girl is brought to the general practitioner by her mother, who has noticed a large dark-brown patch covering most of the upper back since birth. The patch is well-defined, slightly raised, and covered with fine dark hair, and there are about a dozen smaller dark-brown spots scattered over the rest of the back and the shoulders. The girl was born at term, she is feeding and growing well, and her development is on track. On examination, the patch on the upper back measures fourteen by sixteen centimetres and sits over the thoracic spine, with the surrounding satellite nevi over the back, the shoulders, and the upper arms. The head circumference is on the fiftieth centile, the fontanelle is soft, and the neurological examination is normal. This is a large congenital melanocytic naevus on the posterior axis with multiple satellite nevi — the pattern that raises the concern for the neurocutaneous melanocytosis and warrants the referral to the specialist CMN service and the consideration of the CNS imaging. [2] [6]
Hold the size classification of the CMN by the projected adult size (size lesion will reach in the adult, not the size at birth). Small is under 1.5 cm; medium is 1.5 to 19.9 cm; large is 20 cm and over; giant is 50 cm and over. The risk tracks the size: the small and the medium CMN carry a melanoma risk close to the population risk, and the large and the giant CMN carry the elevated risk that is concentrated in the childhood. The candidate who measures the lesion and the projected adult size, and who names the category, has the risk stratification before the management is chosen. [2] [1]
Overview & Definition
The congenital pigmentary birthmarks are the coloured skin lesions present at birth or appearing within the first year of life, and they are among the commonest findings of the newborn and the infant skin examination. The group spans the benign and the commonplace — the dermal melanocytosis of the Mongolian spot that fades by the age of four, the isolated cafe-au-lait macule, and the small congenital melanocytic naevus — to the rare and the serious — the giant congenital melanocytic naevus with the neurocutaneous melanocytosis, and the syndromic pigmentary pattern of the neurofibromatosis type 1. The skill of the paediatric clinician is to recognise the lesion, to stratify the risk, and to identify the small number of children who need the specialist service and the surveillance. [10]
The congenital melanocytic naevus (CMN) is the hamartomatous proliferation of the melanocytes that is present at birth or appears within the first year as the tardive CMN. It is the lesion that carries the melanoma risk, and that risk is the reason the CMN is distinguished from the other pigmentary birthmarks and managed with the surveillance. The CMN is classified by the size — and specifically by the projected adult size, size lesion will reach when the child is fully grown — because the size is the single strongest correlate of the melanoma risk and of the risk of the neurocutaneous melanocytosis. [1] [2]
The clinical importance of the pigmentary birthmarks lies in three things. The first is the melanoma risk of the CMN, which is concentrated in the large and the giant lesions and which shapes the surveillance. The second is the neurocutaneous melanocytosis, the rare complication of the large posterior-axis CMN with the satellites, in which the melanocytes populate the leptomeninges and carry the risk of the hydrocephalus and the melanoma of the central nervous system. The third is the syndromic significance of the cafe-au-lait macule and the hypopigmented macule, which point to the neurofibromatosis type 1, the McCune-Albright syndrome, and the tuberous sclerosis when the pattern is recognised. [6] [10]
References12ShowHide
- [1]Krengel S, Reyes-Múgica M. Melanoma risk in congenital melanocytic naevi. British Journal of Dermatology, 2017.PMID 28504374
- [2]Krengel S, Scope A, Dusza SW, et al. New recommendations for the categorization of cutaneous features of congenital melanocytic nevi. Journal of the American Academy of Dermatology, 2013.PMID 22982004
- [3]Krengel S, Marghoob AA. Current management approaches for congenital melanocytic nevi. Dermatologic Clinics, 2012.PMID 22800546
- [4]Price HN, O'Haver J, Marghoob A, et al. Practical application of the new classification scheme for congenital melanocytic nevi. Pediatric Dermatology, 2015.PMID 25346440
- [5]Arneja JS, Gosain AK. Giant congenital melanocytic nevi. Plastic and Reconstructive Surgery, 2007.PMID 17632335
- [6]Kinsler VA, Thomas AC, Ishida M, et al. Multiple congenital melanocytic nevi and neurocutaneous melanosis are caused by postzygotic mutations in codon 61 of NRAS. Journal of Investigative Dermatology, 2013.PMID 23392294
- [7]Caccavale S, Calabrese G, Mattiello E, et al. Cutaneous Melanoma Arising in Congenital Melanocytic Nevus: A Retrospective Observational Study. Dermatology, 2021.PMID 33053549
- [8]Zalaudek I, Conforti C, Guarneri F, et al. Clinical and dermoscopic characteristics of congenital and noncongenital nevus-associated melanomas. Journal of the American Academy of Dermatology, 2020.PMID 32360715
- [9]Elisabeth Wramp M, Langenbruch A, Augustin M, et al. Clinical course, treatment modalities, and quality of life in patients with congenital melanocytic nevi - data from the German CMN registry. Journal der Deutschen Dermatologischen Gesellschaft, 2017.PMID 28214318
- [10]Dohil MA, Baugh WP, Eichenfield LF. Vascular and pigmented birthmarks. Pediatric Clinics of North America, 2000.PMID 10943257
- [11]Tey HL. A practical classification of childhood hypopigmentation disorders. Acta Dermato-Venereologica, 2010.PMID 20107718
- [12]Oei W, Fledderus AC, Spuls PI, et al. Development of an international core domain set for medium, large and giant congenital melanocytic naevi as a first step towards a core outcome set for clinical practice and research. British Journal of Dermatology, 2021.PMID 33237568